METABOLIC CHANGES IN THE BRAIN DURING TRANSIENT ISCHEMIA MEASURED WITH MICRODIALYSIS

Forty-four patients with severe head injury were monitored for episode s of cerebral ischemia using jugular venous oxygen saturation (sjvO(2) ), brain tissue pO(2) (ti-pO(2)), and a microdialysis probe. The conce ntration of lactate and glucose were measured in the microdialysate. A total of 10 episodes of global ischemia were observed The characteris tic pattern of a simultaneous decrease in sjvO(2) and brain ti-pO(2) w ith an increase in the concentration of lactate occurred in all 10 pat ients. In addition, 3 episodes of regional ischemia were observed. Alt hough brain ti-pO(2) decreased to very low values and the concentratio n of lactate increased in the microdialysate, sjvO(2) remained unchang ed. Brain ti-pO(2) adds another dimension to our cerebral monitoring b y allowing the detection of regional cerebral ischemia.